Drill grinder



June 4, 1946.

I H. E. FENDRING DR ILL GRINDER Filed Feb. 7, 1944 Patented June 4, 1946 UNITED STATES PATENT OFFICE DRILL GRINDER Harry E. Fendring, Los Angeles, Calif.

Application February 7, 1944, Serial No. 521,375

3 Claims. 1

My invention relates to a drill grinder, and more particularly to an attachment to conventional grinders, for grinding drills of most common sizes.

An object of this invention is to provide a drill grinder for grinding drills of various diameters and lengths, and also for grinding drills of various pitches, that is, drills having flutes of various spirals.

An important object of this invention is to provide a grinder for sharpening extremely short drills, and one which by a'slight conversion or adjustment may be made to sharpen drills of considerable length.

An important object of this invention also is the provision of means whereby the attachment may be quickly adjusted, with respect to the grinding element, to a fixed position which may have been previously determined, or to a fixed position in compliance with specific directions.

A further important object of this invention is to provide means whereby the clearance of the drill back of the cutting lip is relatively uniform so as to increase the strength and the life of the drill. I

Also an important object of this invention is to provide simple and economically constructed means for angularly adjusting the drill-holding member with respect to the supporting means therefor so that the angular position of the trough may be easily and quickly determined.

With the foregoing objects in view, and others, as will appear hereinafter, I have provided a specific construction of my drill grinder embodying the foregoing objects, as will be described hereinafter, and shown in the accompanying drawing, in which:

Fig. 1 is a side elevational view of my drill grinder in a preferred form;

Fig. 2 is another elevational view thereof, taken at right angles to that shown in Fig. 1, but from the drill-grinding end of the attachment;

Fig. 3 is a rear end view of the drill-holding member, taken at 3-3 of Fig. 1, a portion being broken away to clarify the illustration.

Fig. 4 is a section view thereof, taken through 5-4 of Fig. 1;

Fig. 5 is a fragmentary sectional view thereof, taken through 5-5 of Fig. 2;

Fig. 6 is a sectional view thereof in plan, taken through B6 of Fig. 1, showing the base of the pedestal;

Fig. 7 is a fragmentary side view of the drillholding trough, showing how the same may be used as a gauge to determine the approximate angle of the clearance; and

Fig. 8 is a side view of the adjusting screw, but with another adjusting drill stop mounted thereon for use, as shown in the dotted line position in Fig. 1. g

In the drawing, the grinding element which may be a conventional grindstone, is designated W, and the support therefor may be a table,

pedestal, or other support T, for the grindstone.

My attachment is adjustably mounted on the table T. The supporting pedestal, designated I, of the attachment, is provided with an elongated base I which has a slot l This base is adjustably secured to the table T by a bolt 2 extending through the slot I. On the face I and along side the slot I is a graduated scale 3 for determining the position of the drill relative to the grinding wheel W.

At one end of the base of the pedestal l is an upwardly directed ivot pin l, and over this pin is swivelly mounted the cylindrical stem 4* of a support 4. The pivotal axis of the support 4 on the pivot pin of the base is inclined at an angle from the base toward the grinding wheel W, preferably and substantially as shown in Fig. l, for the purpose to be hereinafter described.

At the upper end of the support is a pivot portion 4 on which is carried a V-shaped drillholding trough 5. This drill-holding trough or member is provided with a downwardly extending pivot boss 5 which is positioned against the apex of the drill-holding trough is positioned considerably to one side of, and specifically to the left-hand side of the pivotal axis and of the support 4, as shown best in Fig. 2, also for the purpose to be hereinafter described.

In order to determine and fix the angular position of the trough 5 with respect to the support 4, I have provided a plurality of radial notches 4 in the pivot portion 4*, in one of whichis adapted to extend a radial ridge E on the lug 5 At the upper end of the trough, that is, the end nearest the grinding wheel W, is a drill grinding guide lip 1, which consists of a piece of hard plate steel. One edge of the lip is pivotally mounted at its lower end, by a screw 8, at one end of one leg of the trough '5, and below the face of said leg. The opposite end of the lip 1 is provided with an arcuate slot '1 which is adjustably secured to the outer end of this leg of the trough by a screw 9. This permits the upper edge l of the lip to be raised and lowered, or variously inclined, with respect to the upper face of said leg of the drill-holding trough upon which it is mounted.

The adjustment of the guide lip, as stated, permits the proper sharpening and adjustment of drills of various twists or spirals.

The trough 5 is V-shaped, with the legs or flanges substantially at right angles to each other. The drill to be sharpened is laid. in this trough with the opposite edges of the flute, near the cutting edge, resting on the upper edge 1* of the lip 1. The drill is adjusted within the trough and upon the lip I and relative to the grinding wheel by means of an adjusting stop or feed member In. One end of the stop lies within the trough at right angles to the longitudinal extent or axis thereof, and the other end of the adjustable stop is provided with a threaded boss m through which the adjusting screw H extends. The adjusting stop is carried upon the adjusting screw substantially from one end of the trough to the other. The screw is manually rotated by a knob l I at the lower end thereof. The adjusting stop is locked in position by a lock nut l2 at the upper end of the adjusting stop. The upper end of the adjusting screw is reduced and fits into and is revolubly mounted in lugs 5, while the lower end is mounted in a lug 5 these lugs being positioned at the upper and lower ends of one side of the trough.

The lower end of the screw H is undercut, as indicated by ll in Fig. 8, and this undercut portion fits into a bifurcated portion of the lower supporting lug 5 One side of the undercut portion is flattened, as indicated by W, to permit this portion to be readily snapped into the 1115; 5 and also readily removed therefrom.

If a drill of unusual length is to be sharpened, the screw is removed from the position shown in Figs. 1, 2, 3, and 4, and the upper end thereof, is secured to a lug 5 extending downwardly and spaced from the lower end of the trough. This lug is provided with a hole, which is axially parallel to the apex of the trough, and which consists of a tapped portion 5 and a counterbored portion 5' for receiving respectively the threaded portion and the reduced portion at the upper end of the screw. In this position the screw extends downwardly beyond the lower end of the drillholding trough, as indicated by dotted lines in Fig. 1.

When the screw is in the last-mentioned position, there is provided an adjustable stop or feed disc l3, which is screwable on the screw, and which may be locked in position by the lock nut !2. When the attachment is used as last described, the adjustable stop ill may remain on the screw.

I have found by experiment that when the plane passing through the apex of the drillholding trough is positioned at one side of the pivotal axis of the support and pedestal, and specifically at the left side as shown, the desired clearance is provided for the end of the drill. Also, when the pivotal axis of the support 4 is 4 inclined toward the grinding wheel, this clearance on the drill is rounded backwardly from the cutting edge, giving a uniform clearance.

In order to determine whether the clearance is approximately proper, the drill may be laid in the trough, as shown in Fig. '7. The clearance may then be determined by noting the angle between the lower end 5 of the trough and the peripheral line between the ground end and the side of the drill.

In Fig. 1, I have shown a stop S in the form of a nail, which is adapted to be engaged by a stop portion on the swinging trough to limit the swinging thereof on the pedestal. This stop portion may be the lug 5 at the lower side of the trough.

Though I have disclosed a particular form of my drill grinding attachment, I do not wish to be limited to the same, but desire to include in my invention the drill grinding attachment as set forth in the following claims.

I claim:

1. In a drill grinder, a pedestal, a support swivelly mounted on the pedestal, a drill-holding trough carried on the support, an adjusting screw at the side of and parallel to the trough, and an adjustable drill stop mounted on the screw, said adjustable stop extending into and movable in the trough, said trough having means at its opposite ends for revolubly and removably mounting the screw thereon, said trough having also means at the under side thereof for receiving and securing the forward end of the screw so that the screw may extend beyond the lower end of the trough with the axis thereof positioned below and parallel to the apex of the trough.

2. In a drill grinder, a pedestal, a support swivelly mounted on the pedestal, a drill-holding trough carried on the support, an adjusting screw at the side of and parallel to the trough, and an adjustable drill stop mounted on the screw, said adjustable stop extending into and movable in the trough, said trough having means at its oi posite ends for revolubly and removably mounting the screw thereon, said trough having a downwardly extending lug at its underside and spaced forwardlyfrorn its rear end for receiving and securing the forward end of the screw so that the screw may extend beyond the lower end of the trough with the axis thereof positioned below and parallel to the apex of the trough.

3. In a drill grinder, a pedestal, a support swivelly mounted on the pedestal, a drill-holding trough carried on the support, an adjusting screw at the side of and parallel to the trough, said trough having means at its opposite ends for revolubly and removably mounting the screw thereon, said trough having also means at the under side thereof for receivin and securing the forward end of the screw so that the screw may extend beyond the lower end of the trough with the axis thereof positioned below and parallel to the apex of the trough, and an adjusting disc on the screw. 

